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Introduction to EMC Standards, Tests, Equipment and Strategies

Introduction to EMC Standards, Tests, Equipment and Strategies. EMC = Electro-Magnetic Compatibility. Definition: The ability of a product to coexist and safely operate within a set of electromagnetic stresses while not inducing undue electromagnetic stresses

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Introduction to EMC Standards, Tests, Equipment and Strategies

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  1. Introduction to EMC Standards, Tests, Equipment and Strategies J. Kautzer

  2. EMC = Electro-Magnetic Compatibility Definition: The ability of a product to coexist and safely operate within a set of electromagnetic stresses while not inducing undue electromagnetic stresses Example: Use of cell phone on an operating aircraft is prohibited because - Navigational equipment may be effected from field emissions of the phone These EM stresses are standardized and refined into individual tests which are designed to either measure or induce real world effects J. Kautzer

  3. Purpose • The purpose of this tutorial is to give the student an introductory but practical knowledge of the governing standards, tests and strategies involved in the EMC compliance process. • EMC is not magic but …. ! Compliance to EMC is not Easy Cannot typically afford to guess solutions J. Kautzer

  4. Requirements Flowdown:Global Mfgs Typical Quality Policy • States that Company X is committed to comply with the Quality, Safety and Performance regulations of all countries where its products and services are offered This implies conformance to many standards which in turn call for compliance to other standards. J. Kautzer

  5. Medical Equipment Example • New products destined for International Sales mustbe certified to safety standards IEC60601-1 and UL2601-1 as required to show objective evidence that the products are safe. Definition: IEC60601-1 = International Electrotechnical Commission Standard for Medical Electrical Equipment- Part 1, General Requirements for Safety (Many times referred to as IEC601-1 or simply “601”) Definition: UL2601-1 = Underwriters Laboratories Standard for Medical Electrical Equipment - Part 1, General Requirements for Safety Above includes sections on protection from electric hazards, mechanical hazards, excessive radiation, flammabilities, environmental conditions, constructional requirements, and labeling. J. Kautzer

  6. Medical Equipment Example • The IEC60601-1 Safety standard, along with the equivalent US domestic safety standard, UL2601-1, call for IEC60601-1-2 EMC standard Definition: IEC60601-1-2 = IEC Standard for Medical Electrical Equipment - Part 1-2: General Requirements for Safety - Collateral Standard for Electromagnetic Compatibility - Requirements and Test (Many times referred to as IEC601-1-2 or simply the -2 standard) The IEC60601-1-2 standard calls for the use of several IEC and other Standard Tests as described herein Final draft of 2nd Edition of the above standard was approved by the IEC in July of 2001. J. Kautzer

  7. EMC Compliance Has Been Mandated in Many Countries Most Notably in the EC (formerly EEC)EC - European Community • General EMC Directive: 89/336/EEC - 3 May 1999 • Medical Device Directive: 93/42/EEC - 14 June 1993 • R&TTE Directive: 1999/5/EC - 9 March 1999 - Radio and Telecommunications Terminal Equipment and mutual recognition of their conformity • EN 61000-6-2: General Industrial Equipment Immunity Standard • EN 50081-2: General Industrial Equipment Emissions Standard • EN55011: Referenced by EN50081-2, Emission Std for Industrial, Scientific and Medical products • EN61000-6-4: Effective 1 July, 2004, replaces EN50081-2 & EN55011 as Emission Std for Industrial, Scientific and Medical Products J. Kautzer

  8. What are Real World Effects? • Static Discharge by Human Contact • Indirect Lightning Strike Effects • Power Line Surges • Power Line Brown Out and Drop Outs • Power Distribution Reclosures • Cell Phone or Telemetry Transmissions • Field Discharges from Equipment, Lights, Lasers, etc J. Kautzer

  9. ENERGY • EMC compliance is all about measuring energy emitted by the product or …... • Measuring the response of the product to externally induced energy or energy disturbances J. Kautzer

  10. Basic Stresses (Energy Types) • Alternating Electrical Fields • Alternating Magnetic Fields • Conducted Voltages/Currents • Capacitively Coupled Voltages • Electrostatic Voltages • Input Power Source Degradations J. Kautzer

  11. EM Energy EM Energy EM Energy DEVICE DEVICE EMC Tests are divided into 2 Main Categories/Strategies • Emissions - Tests that measure in some way the amount of certain EM energies the device emits or induces • Susceptibility - Tests that measure in some way the effect or responses that EM stresses have on the device performance and safety J. Kautzer

  12. Common Strategies - Test Effectiveness • Like many other Eng or Mfg tests, the quality of the test depends upon minimizing the possibility that a failure can escape. • To this end, all operational modes of a product need to be considered but …. Not necessarily used in all tests. J. Kautzer

  13. Common Strategies - Operational Modes • Modes of Operation - All modes of product operation should be defined & if applicable, tested • Examples: • Idle, Standby, Offline, • Boot, Application, File Send, other SW functions • Battery Powered and Battery Charging (UPS Backups) • Data Xfer to Disk or CD Writing • Xmit, Receive, Measure, Configure, etc J. Kautzer

  14. Common Strategies - Product Options • Product Options and Accessories - All applicable options should be evaluated in the same test if possible or mutually exclusive if necessary • Examples: • Inteface Cables • Metal Bracket Hangers (Metal Grab Bars) • Operator Console Stands, Pedestals, Monitors • UPS Backups, AC charging modules • Wall Plates • External Network Connections, Option Cables, etc J. Kautzer

  15. Common Strategies - 2 Basic Test Types • Engineering Test - Test used for baselining a product but not necessarily using official equipment and process for official certification results. Often Eng tests use higher levels of stress. • Certification Test - Official tests used to show objective evidence of satisfying spec such as IEC60601-1-2. • Technical Justification - Formal document which may utilize previous certification or engineering test data that justifies a claim of compliance. J. Kautzer

  16. Common Strategies - Subsystems vs System • System Test - Defined as a test of a full end user product. System must be certification tested and/or show compliance to all applicable tests from parent standard such as IEC60601-1-2. Systems in production are retested typically 1/yr as an audit process to show compliance. • Subsystem Test - Defined as a test of one element or subsystem which may not be an end user product. SS test necessity depends on System Cert strategy as well as CE marking of the SS but is always beneficial. • Susceptibility Tests - Stress levels are well defined and a strategy is employed to gauge and classify the response level of the product to find the highest sensitivity stress and product area J. Kautzer

  17. EM Energy EM Energy DEVICE Strategy Differences • Emissions Tests - Allowable limits are well defined and a strategy is employed to find the maximum energy the product will induce • Susceptibility Tests - Stress levels are well defined and a strategy is employed to gauge and classify the immunity response level of the product to find the highest stress sensitivities DEVICE J. Kautzer

  18. EMISSIONS • Radiated - RF (Radio Frequency) Electric Field measurements taken between 30 MHz and 1 GHz • Conducted - Voltage Measurements made on input power lines between 150 kHz and 30 MHz • Requires Product to be Powered on 50 Hz J. Kautzer

  19. EMISSIONS • Governed by CISPR11/EN55011: International Special Committee on Radio Interference • Product classified depending on if RF energy is intentionally used: Group 2 (MR for example) or Group 1 • USLs Defined by Product intended application • Class A: Non Domestic Use • Class B: Domestic Use, More stringent J. Kautzer

  20. RADIATED EMISSIONS • Electric Field is measured on a calibrated site using a receiving antenna and attempts to find worst-case emission amplitudes by varying product geometry and field orientation. J. Kautzer

  21. CISPR11- RF Emissions • Test Name: Radiated E Field • Energy/Stress: Induced Electrical Field (dBuV/m) • Class A Limit: 30-230 Mhz = 39.5dBuV/m @ 10 meters • Class A Limit: 230-1000 Mhz = 46.5dBuV/m @ 10 meters • Class B Limit: Class A Limit - 10dBuV/m • Purpose or Real World Effect - This test is designed to determine if the RF energy emitted by the product falls within reasonable limits to prevent interference. These levels are classified as Class A or the more stringent Class B level. J. Kautzer

  22. CISPR11- RF Emissions • Equipment Used: • OATS: “Open Area Test Site” - Large Area or Room typically built upon conductive ground plane. May also be done in fully shielded anechoic 10 meter chamber. • Antenna: Calibrated receiving antenna(s) • Positioning for 10 Meter Open Air Test Site: • Means to rotate field orientation 360 degrees while operating • Means to orient field horizontally or vertically • Means to raise/lower field (antenna orientation between 1 and 4 meters above ground plane) • Receiver, Spectrum Analyzer and Data Logger (Field Strength versus Frequency Gauge) J. Kautzer

  23. OATS Test Equipment Analysis Equipment Bicon and Antenna Mast J. Kautzer

  24. OATS 8 Meter Diameter Circular Turn Table Field Antenna 10 Meters Must be Capable of Testing Any Product Configuration J. Kautzer

  25. CISPR11- RF Emissions • Basic Permutations: • System operational modes • 30 Mhz to 1 Ghz frequency sweep in 30 incremental bands • 0 to 360o field rotation about Vertical axis with respect to receiving antenna mast • 1 to 4 meter height of receiving antenna above ground plane • Vertical and Horizontal field (antenna) orientation • Test time: • Highly dependent on test type, changes in product from last test, number of failures, support staff for root cause and corrective actions. J. Kautzer

  26. CISPR11- RF Emissions • OATS E Field Testing Methods: • Product Operational Modes: All Applicable Modes of Operation. Any mode should be tested in which it is likely there is a substantial change in basic use of subsystems, clocking of high speed circuits, motor drives, power loading, display operation, data paths, etc. • Positioner: Product is rotated from 0 to 360 degrees on an 8 Meter turn table to find maximum field emissions within a given band of frequencies. Maximums are noted for further optimizations using other axis of positioning. • Antenna: Antenna is 10M to product, adjusted for vert or horz field orientation as well as moved from 1 to 4 meters above ground plane. • Receiver and Spectrum Analyzer: The 970 Mhz bandwidth is broken into narrower bands (total of 30) each which is individually checked. Careful attention must be paid to ambient emissions in order to omit/subtract them from the test results. J. Kautzer

  27. OATS Turntable: Cables suspended 10cm above Ground Large Product System on OATS Turntable J. Kautzer

  28. CISPR11- RF Emissions • Cautions: • Traditionally most difficult/costly test of IEC60601-1-2 • Test should be conducted by qualified operator • Hidden emission behind ambient frequencies. Particularly if external test is employed in a different location • Calendar time of test may vary depending upon • Weather - Thunderstorms affect or stop testing due to safety concerns and/or interference from lightning • Failures - Modifications take time and may cause test restart • First or Nth test - Products with no previous test data will take longer as there is no prior knowledge of operational modes • Cable Placement will greatly affect results (Document Them!) • Corrective Actions may be time consuming and costly J. Kautzer

  29. CONDUCTED EMISSIONS • Voltage is measured using a calibrated Line Impedance Stabilization Network (LISN), with spectrum analyzer (gauge which measures voltage amplitude versus frequency) and is protected by a transient limiter. J. Kautzer

  30. CISPR11- Conducted RF • Test Name: Conducted RF Emissions • Energy/Stress: RF Voltage (dBuV) • Purpose or Real World Effect - This test is designed to determine if the RF energy conducted by the product back onto the input power lines is within level which will likely not cause interference. These levels are classified as Class A or a more stringent level Class B. J. Kautzer

  31. CISPR11- Conducted RF • Equipment Used: • Typically Done in shielded room • Coupler which limits transients and Spectrum Analyzer (Voltage Amplitude versus Frequency Gauge) • LISN - Line Impedance Stabilization Network • Coupling: Conducted • Permutations: Sweep frequency from 150kHz-30MHz, each power line phase, system operational modes J. Kautzer

  32. IEC 61000-3-2 • Name: Powerline Harmonics • Energy/Stress: Voltage Harmonics induced back onto Main power connections • Simulates Real World Effect – Mains network waveform distortion and excessive 3 phase neutral line current for product with rated line current <= 16Amps /phase • Equipment Used: Power line analyzer • Coupling: Conducted • Permutations: 2nd to the 40th harmonic, Steady State and Fluctuating Harmonics J. Kautzer

  33. IEC 61000-3-3 • Name: Voltage Fluctuation and Flicker • Energy/Stress: Voltage Fluctuations induced by product • Simulates Real World Effect – Voltages fluctuations from product cause mains powered lighting to flicker. For product with rated line current <= 16Amps /phase • Used: Power line analyzer • Coupling: Conducted • Permutations: None • Supercedes IEC60555-3 previous standard. J. Kautzer

  34. Power Line Analyzer Setup J. Kautzer

  35. SUSCEPTIBILITY(IMMUNITY) • Radiated - RF (Radio or High Frequency) Electric and Low Frequency Magnetic Fields • Conducted - Voltage Pulses of varying duration and energies including electrostatic voltage • Conducted - RF Voltage (high frequency voltage) • Conducted - Unstable AC power source J. Kautzer

  36. SUSCEPTIBILITY(IMMUNITY) Response ?? • Product Response Summary per (EN61000-6-2): • Level (A) 1: No discernable change in product operation and function • Level (B) 2: Safe effect is noted in the product operation or function. Effect disappears when stress is removed without intervention. • Level (C) 3: Safe effect is noted in the product operation or function. Effect requires operator intervention to completely recover after stress is removed. • Level (D) 4: Safe effect is noted in the product operation or function. Effect requires service intervention to completely recover when stress is removed. (Repair) J. Kautzer

  37. SUSCEPTIBILITY(IMMUNITY) Criteria A • Product Response Detail per (EN61000-6-2): • Criteria A (Level 1): “The apparatus shall continue to operate as intended DURING and AFTER the test. No degradation of performance or loss of function is allowed below a performance level specified by the Mfg when the apparatus is used as intended. The performance level may be replaced by a permissible loss of performance. If the minimum performance level or the permissible loss is NOT specified by the Mfg, either of these may be derived from the product description and documentation, and from what the user may reasonably expect from the apparatus if used as intended.” J. Kautzer

  38. SUSCEPTIBILITY(IMMUNITY) Criteria B • Product Response Detail per (EN61000-6-2): • Criteria B (Level 2): “The apparatus shall continue to operate as intended AFTER the test. No degradation of performance or loss of function is allowed below a performance level specified by the Mfg when the apparatus is used as intended. The performance level may be replaced by a permissible loss of performance. During the test, degradation of performance is however allowed. No change of actual operating state or stored data is allowed. If the minimum performance level or the permissible loss is NOT specified by the Mfg, either of these may be derived from the product description and documentation, and from what the user may reasonably expect from the apparatus if used as intended.” J. Kautzer

  39. SUSCEPTIBILITY(IMMUNITY) Criteria C • Product Response Detail per (EN61000-6-2): • Criteria C (Level 3): “Temporary loss of function is allowed, provided the function is self-recoverable or can be restored by the operation of the controls.” J. Kautzer

  40. SUSCEPTIBILITY(IMMUNITY) • Any response other than Level 1 requires that response/mode warning to be disclosed in operator /service manual • Governed by many different IEC test standards in the IEC61000-4 series • Most good product designs require Level 1 or 2 responses although many products fail to meet it and are inadequately informing the user • Any unsafe response to any of the series of tests is not allowed! (Levels 5 and higher) J. Kautzer

  41. IEC61000-4-2 • Test Name: Electro Static Discharge (ESD) Immunity • Energy/Stress: Electrostatic Voltage • Simulates Real World Effect - ESD from human contact. Low humidity, low conductivity carpets, upholstery & garments are contributors • Equipment Used: Electrostatic Discharge Gun J. Kautzer

  42. IEC61000-4-2 • Coupling: Air Discharge, Direct Contact & Coupling Plane Discharge • Permutations: • Discharge points: Likely points of human contact with product including keyboards, monitors, operator controls, cabinet exteriors, removable media drives • Air or Spark Gap Discharge: 2000 volt increments to 8 kV • Direct Contact/Coupling Plane Discharge: 2000 volt increments to 6 kV • Positive and Negative Polarities for each discharge point • 10 hits per each discharge point J. Kautzer

  43. IEC61000-4-2 • Coupling Plane Discharge used for keyboard and mouse test J. Kautzer

  44. IEC61000-4-3 • Test Name: Radiated E-Field Immunity • Energy/Stress: Radiated Electromagnetic Voltage • Simulates Real World Effect – Radiated Frequency signals from Cell Phones, Radios, Cell & TV towers, CB’s , PC’s & other various electronic devices • Equipment Used: • RF Power Amplifier • Signal Generator Capable of Modulation • Transmitting Antenna and Isotropic Probe • RF Power meter • RF Directional Coupler & RF Reverb Chambers J. Kautzer

  45. IEC61000-4-3 (Rev 002) • Permutations: • Operational Modes including Imaging Modes • 3V/M RF Electric Field • RF Carrier is varied in 1% steps from 80Mhz to 2.5Ghz • Amplitude Modulation using 80% modulation factor @ 1kHz, Dwell Time (product response time) • As many as 56 Tuner (Horz and Vert Reflector) steps which covers 80% of the room height and width (80-300 Mhz) J. Kautzer

  46. IEC61000-4-3 (Rev 002) • Test Time: ~35 hours per operational mode using 6 second dwell time between steps. 6 seconds/step plus 6 second dwell time per step. (~10,500 total steps/mode!) • Initial testing may require longer dwell times to gauge product response • Only test the modes that are absolutely necessary! • Reverb chamber with “mode-stirs” must be utilized. Expensive! Need to plan test time and mode strategy well in advance! J. Kautzer

  47. IEC61000-4-4 • Test Name: Electrical Fast Transient & Burst (EFT) • Energy/Stress: Voltage Transients up to 2000 Volts • 50 nS Pulse with 5ns rise times - ~400V/nS • Simulates Real World Effect – Created on public power lines by electrical arcs across switch contacts during opening of inductive loads such as relays, motors and other commutations • Equipment Used: Coupler, Transient Generator & Scope • Coupling: Capacitive (I/O Cables) & Direct Injection (Main Power Input Cables). Capacitive coupling is a 1 meter long cable clamp of parallel plates. Energy goes right through the cable jackets! J. Kautzer

  48. IEC61000-4-4 • Permutations: • 500 Volt Increments • 2 Minutes/step • Positive and Negative Pulse Polarities for each Increment • AC Mains receive up to 15 injection points • I/O Cables > 3M length require both ends be tested up to 1 Kv • Main Power Cables are tested at up to 2 Kv regardless of length • Cautions: Must be done in shielded room as the test may create a large amount of RF energy J. Kautzer

  49. IEC61000-4-4 • Electrical Fast Transient Generator with Coupling Circuits J. Kautzer

  50. IEC61000-4-5 • Test Name: Power Input Surge Immunity • Energy/Stress: Voltage Surge Pulse • 50 uS open-circuit voltage pulse with 1.2 uS rise time • 20 uS short-circuit current pulse with 8 uS rise time • Simulates Real World Effect – Voltage surges caused by lightning discharges and switching disturbances in power stations • Equipment Used: Coupler, Surge Generator & Scope • Coupling: Direct Injection into System Mains Power) J. Kautzer

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